Impulse generator for telemetering systems



May 31, 1949. s. M. GRANNIN! 2,471,947

IMPULSE GENERATOR FOR TELEMETERING SYSTEMS Filed June 4, 1945 2Sheets-Sheet 1 INVENTOR. GABRIEL M. GIANNINI ATTORNEYS May 31, 1949. a.M. GEANNINI 2,471,947

IMPULSE GENERATOR FOR TELEMETERING SYSTEMS Filed June 4, 1945 2Sheets-Sheet 2 INVENTOR. GABRIEL M. GIANNINI ATTORNEYS Patented May 31,1 949 IMPULSE GENERATOR FOR TELEMETEBING SYSTEMS Gabriel M. Giannini,West Los Angeles, Calif.I alslgnor, by mesne assignments, to Howe &Fant, Inc., South Norwalk, Conn., a corporation of Delaware ApplicationJune 4, 1945, Serial Masonite 5 Claims. 1

This invention relates generally to telemetric systems; that is, tosystems of the follow-up type, including systems which are designed toperform the function of remote indication or of transmission ofintelligence, and systems which perform the function of remote operationor remote control. The invention has useful applications and utilitiesin connection with all such operations; being generally useful in a reatmany if not all situations in which it is desired to perform any suchfunctions.

Without implying any limitations, but merely for example, telemeteringsystems of the type herein described are especially useful in aircraftoperation, for the purpose of transmitting information concerned withlanding gear position, oil ressure, gasoline pressure, enginetemperature; and likewise the system is importantly usei'ul in theremote control and operation of such conditions and of such devices.Other fields of utility are, for example, in automatic telephony,signalling and switching operations, and in computing machines ofvarious kinds and types. 7 The general function performed by the systemin all such applications and uses, is the stepped operation or actuationof a follow-up device or receiver in consonance with the operation ormovement of the initial operator or transmitter in either of twoopposite directions. The system performs algebraically in the sense thatit actuates the receiver selectively in both plus and minus directions,to add or subtract.

One characteristic feature, and object, of my invention in one of itspreferred forms, resides in its creation and utilization of succeedingelectrical impulses of positive or negative sign, depending upon thedirection ofmotion of the transmitter. The motion of both transmitterand receiver, in the practical and preferred form of the system which Ishall describe here, is preferably rotary; and so Ishall refer to themotions as rotation, but without implying necessary limitation thereto.Assuming rotational movement, the transmitter delivers a measured seriesof integer impulses ofone sign on rotation in one direction, one impulsefor each angular unit of movement; and on rotation in the oppositedirection delivers a similarly measured series of integer impulses ofthe opposite sign. The two series of impulses of opposite signs causethe receiver to rotate selectively in one direction or the oppositedirection, depending upon the sign of the received impulses.Consequently, if both the transmitter and receiver are initially set incorresponding positions, the operation of the system will cause the twomechanisms to move in consonance with each other, the accuracy ofconsonance being only limited by the size of the angular movement whichis adopted as a unit or step. That unit or step, as will hereinafterappear, may be made as large or as small as may be desired or necessaryin any particular installation. And, in any given installation theangular measure of the unit or step of movement may be varied over therange of operation to make the system more accurate in its followingfunctions throughout some predetermined part of the range.

Another feature of the invention is that the system is self-energized,not depending upon a separate or external source of electrical energysuch as a battery. Another feature of the invention is that the systemconstitutes a continuous non-interrupted circuit employing no contactsand requiring the actuation of no switches.

The preferred form of transmitter, as will be described, is one whichgenerates distinctly separated electrical pulses of relatively highamplitude which amplitude does not depend materially upon the speed ofoperation of the initial driver or transmitter. The transmitter is, ineffeet, a mechanism in which energy'from the ori inal driver is storedand periodically released, the released energy being expended through arelatively short period of' time to create each time a high amplitudepulse. The mechanism for performing those functions is preferably of amagnetic ratchet nature, involving no relatively moving parts inmechanical engagement with each other and thus involving no wear. Theratchet mechanism which I prefer is in the nature of a magneticmechanism which operates an oscillatory generating magnet slowly in onedirection and at high, speed in the opposite direction of oscillation,the orientation of those directions be ing fixed with reference to thedirection ofrotation of the initial driver and the ratchet mechanism sothat, on initial rotation of the driver in one direction the fastoscillatory movement of the generating magnet will be in one direction,and on initial rotation in the opposite direction the direction of fastoscillatory movement of the generating magnet will be reversed.

The receiver of the systemfunctions to actuate a driven memberstep-by-step in either of two opposite directions, in accordance withthe sign of the received impulse or impulses. Its characteristics andfeatures and its preferred structure and mode of operation will be laterdescribed in detail.

istics of my system is its continued positiveness and accuracy ofoperation throughout long use, and its very small liability toderangement from any external or internal cause. The actuating pulsesare sharp and definite and of relatively high amplitude, and since theyare generated internally in the system, the system as a whole is freefrom liabilities of being disabled by such causes as the failure of anenergizing battery or generator, the blowing-out of protective fuses orthe inadvertent or malicious operation of switches. a

Other accomplishments, characteristics and corresponding objects of theinvention will appear from the following description wherein referenceis had to the accompanying drawings in which Fig. 1 is a perspectiveshowing one preferred form of my transmitter; M

Fig. 2 is a fragmentary diagrammatic side view of portions of thetransmitter of Fig. 1, showing the driving and driven magnets of themagnetic ratchet mechanisntand also the generating magnet, and alsoshowing a primary driver;

Fig. 2a is a view in elevation taken as indicated by line 2a2a on Fig.2;

Figs. 3 and 4 are fragmentary front elevations of a preferred form ofreceiver, in different operating positions;

Fig. 5 is a perspective of the preferred form of receiver; and

Fig. 6 is a schematic circuit diagram of the telemetric system utilizingthe illustrated preferred forms of transmitter and receiver.

The preferred form of the transmitter shown in Figs. 1 and 2 comprises asystem of four coils 3, 4, 5, 6, preferably wound on cores 2 which aremounted on a base i. Both cores and base are preferably of soft iron.The cores and coils are symmetrically arranged about the axis of acentral rotatable shaft 7 which carries the oscillating generator 8which, in this case, is preferably a highly magnetized bar. Inoperation, the generating magnet ii oscillates between the two positionsshown in full and dotted lines in Fig. 6; that is, between a position inwhich it closes the magnetic circuit between the cores of coils i and 6(the position shown in Fig. 1) and a position in which it closes themagnetic circuit between the cores of coils 3 and 5 (the position shownin dotted lines in Fig. 6). Preferably the generating magnet 8 ipositively stopped in both its terminal positions and, although the stopmay be of any suitable physical kind, I prefer to use a simplearrangement in which generating magnet ii brings up directly againstnon-magnetic inserts 2a in the ends of cores 2.

As will appear, it is not necessary that the member 8 itself bemagnetized. It is sufficient for the operation of the system that anyone or more of the magnetic circuit elements be magnetized, eitherpermanently or by an electrically energized coil. Thus, in the followingdescription of operation it may be assumed either that mem-- ber 8 ismagnetized and that cores 2 and base i are of soft iron (the preferredarrangement) or that member 8 is of soft iron and cores 2 or base I aremagnetized. In either case, upon oscillatory movement of member 8 fromthe position shown in full lines in Figs. 1 and 6 to the position shownin dotted lines in Fig. 6, the magnetic flux in the magnetic circuit ofcoils t'and 5 will be increased, while the flux in the magnetic circuitof coils 4 and 6 will be decreased. On oppositemovement of l, oppositechanges in the fluxes will occur. I

The four coils may be connected in series (pref erably so) or inmultiple, or in series multiple; but in any event the connections aresuch that the current induced in the several coils by the changes of;vagnetic flux are in additive relation. Thus, considering a seriescircuit such as shown in Fig. 6 and tracing that circuit through fromone end to the other, the windings of coils 3 and 6 will be in one andthe same direction and the windings of coils 4 and 5 in the oppositedirection. Consequently, on movement of member 8 from the full line tothe dotted line position of Fig. 6 an additive current or voltage 'pulsewill be generated in the four coils and. for simplicity of description,it may be assumed that on that movement a positive pulse voltage isgenerated in conductor 40 leading from the transmitter. On oppositeoscillatory movement of generating member 8, from the dotted line to thefull line position of Fig. 6, a pulse of opposite or negative signs willbe generated in conductor 40.

It is to be observed that the same pulse generations'will take place incircuit 40 without the necessity of four coils. For instance,considering only one coil, say coil 5, the oscillatory movement ofgenerator 8 to and from the vicinity of that coil or its core willgenerate pulses of opposite signs on opposite movements. The same istrue if pairs of coils are used; for instance, the pair 5, 6, the pair5, 3, or the pair 5, 6. However, the arrangement illustrated ispreferred, both for efficiency of pulse generation and for static anddynamic balance in the instrument; the latter being particularlyimportant where the system is subject to vibrations and. to acceleratingforces, as in aircraft.

It is the general function of the magnetic ratchet mechanism to movegenerating member 8 from one of its positions to the other positionrelatively slowly so as to cause a slow change of magnetic flux duringthat movement, and then to move the generating member from its lastmentioned position to its initial position at high velocity so as tocause relatively rapid change of magnetic fiuxduring that movement; andalso to cause the orientations of the slow and fast movements to reversewhenever the rotational direction of the initial driver reverses. Apreferred illustrative form of magnetic ratchet mechanism is shown inFigs. 1 and 2.

As shown in those figures the ratchet mechanism comprises six barmagnets, two driven magnets 9 solidly connected to rotate withgenerating magnet t, and four driver magnets H which are rotatable as awhole, independently of the driven magnets 9, without any necessarylimit in either direction. As illustrated in the drawings, driven magnetsystem a is rigidly mounted on the shaft l on which generating magnet 8is also rigidly mounted, so that the two magnetic systems oscillatetogether. And driving magnet system i l is shown as rigidly mounted on ashaft l9 concentric with but free of shaft 1. Shaft i0 is rotativelydriven by or from the element which I here call the primary driver,indicated diagrammatically at l2 in Fig. 2, and which may be any movableor rotatable element. For instance in a system of remote control orremote actuation, element l2 may be nothing more than a manually movablehandle or dial. Or, in systems where it is desired to give a remoteindication of an existing variable condition. element l2 will itself be,or be connected to, the member, de-

vice or mechanism whose position or condition is to be remotelyindicated. For explanatory purposes, but without limitation, I willassume that element I 2 is, for example, a pressure gauge and that shaftI is so connected to the gauge that it rotates back and forth aspressure rises and falls. In consonance with this assumption, thereceiver (hereinafter described) will operate an indicator of pressure,such as an indicator pointer travelling over a calibrated dial. However,as has been indicatedherein, the receiver is capable of actuating anysuitable indicator, device or mechanism depending upon the use to whichthe system is put.

As illustratively shown in the drawing the driven magnetic system 9 iscomposed of two magnetized bars extending on opposite sides of shaft 1and having their two outer ends magnetized to the same polarity, sayNorth. Also as illustratively shown, driver magnetic system Il comprisesfour radial magnets Ila, b. He, Itd, magnetized to alternate terminalpolarities. The radial lengths of all the magnets 'are substantiallyequal, and the magnetic system I I rotates in a plane close to the planeof oscillation of the driven magnetic system 9, so that during rotationthe poles of magnets Ilwill approach closely to the poles of magnets $3.

In explaining the operation of the ratchet mechanism I will assume thatthe parts initially stand in the relative positions shown in Fig. l andthat shaft It and the driving magnet system II are being rotatedcounter-clockwise. In'that counter-clockwise movement the South pole ofmagnet I It is approaching the upper North pole of driven magnet 9. Asthese two poles approach each other the attraction of H21 for 9increases,

but driven magnet 9 cannot move toward magnet' IIb because it andgenerating magnet 8 are at the limit of their movement in that direction(clockwise). Driving magnet Ilb approaches driven magnet 9, finallyreaching a position in opposition to it, and then starts to move awayfrom it. The magnetic strength of the magnets in the ratchet system ismuch greater than the.

magnetic strength of generating magnet d or of the magntic circuit ofwhich it forms a part.

Consequently, as driving magnet IIb begins to move away from drivenmagnet 9, exerting an intense attractive force on the latter, thatdriven magnet immediately begins to follow driving magnet I I b. Theattractive force of generating magnet 8 for the cores 2 is overcome bythe much larger attractive force of magnet IIb for magnet 9; so thatmagnet 9 follows magnet IIb closely, travelling at substantially thesame speed as the latter, until generating magnet I is moved from theposition shown in Fig. 1 and in full lines in Fig. 6, to the positionshown in dotted lines in Fig. 6, where it brings up against cores 2 ofcoils 3 and 5. This movement of the generating magnet is comparativelyslow and only causes the generation of a small or negligible pulseamplitude in the coils.

In the continued counter-clockwise rotation of the magnetic drivingsystem II the North pole of magnet Ilc next approaches the upper Northpole of magnet 9. That magnet 9, and generating magnet 8, being now atthe limit of their counter-clockwise movement, the repulsive action ofMe on 9 has no eiIect until He has just passed 9. When that occurs theattractive hold ofgenerating magnet I on cores 2 of coils 3 and 5 isbroken by the much larger repulsive force between the like poles of Heand I, and driven magnet 8 is consequently repelled in a clockwisedirection at high velocity, to its initial position shown in Fig. 1.During this high velocity snap action the magnetic flux in the magneticcircuits'of coils 4 and 6 is rapidly increased, and in those of coils 3and 5 is rapidly decreased. resulting in a high amplitude pulse of shortduration. According to the descriptive convention here adopted, thatpulse would be negative.

With the parts back in the position of Fig. l. the next driving pole toapproach the upper North pole of driven magnet 9 will be the South poleof driving magnet I Id. As it comes'opposite and begins to pass theNorth pole of magnet t, the latter will follow it slowly just as itpreviously followed the South pole of magnet lib; and the driven magnetand generating magnet 8 will thus again be moved slowly to the limit oftheir counter-clockwise movement. And then when the North pole ofdriving magnet IIa next approaches and passes. the upper North pole ofdriven magnet 9, the high velocity snap action of the driven magnet andthe generating magnet in a clockwise direction will be repeated,accompanied by a second high amplitude negative pulse in the coilcircuit. On successive counter-clockwise passages of the alternatingpoles of the driving magnets, the driven magnet and the generatingmagnet will be alternately moved slowly in a counter-clockwise directionand then driven in high velocity snap action in clockwise direction.

Assuming on the other hand that the driving magnetic system is rotatedin a clockwise direction it will be seen without the necessity ofdetailed explanation that on the alternate clockwise passage of theSouth and North poles of the driving system, the North pole of drivenmagnet 9 will be alternately moved slowly in a clockwise direction anddriven in high velocity snap action in a counter-clockwise direction. Inthe slow clockwise movement the pulse generated in the coils has low ornegligible amplitude, while in the fast counter-clockwise movement ofthe generating magnet a pulse of short duration-and high amplitude isgenerated, of positive sign according to the descriptive convention.

It is assumed that the angular velocity of the driving magnetic systemII is considerably less than the angular velocity of the snap actionwhich generates the high amplitude pulse. Or, putting the matter inanother way the constants of the transmitter will be designed in anyparticular case so that the angular velocity of the snap action isdefinitely greater thanthe maximum angular velocity with which'thedriving magnetic system I I is rotated; so that in every case the.amplitude of the pulse generated by the snap action will be materiallygreater than the amplitude of the pulse of opposite sign generated bywhat may be called the setting action of the ratchet mechanism. In fact,in a great variety of uses and installations, the angular velocity ofdriving magnet II is relatively so slow that the pulse generated duringthe setting movement is of substantially zero or negligible amplitude.In any case, the pulse amplitude generated by the snap action should beat least, say, three times the maximum pulse amplitude generated duringthe pulse period so as to keep successive pulses distinctly separatedand allow the receiver ample time to return to normalposition after eachpulse actuation. For instance if the driving magnetic system operates atone hundred cycles per secend, the pulse period should be limited to,say. iive thousandths of a second or less.

The description so far has assumed that there is only one driven magnetd, 'iresenting one terminal pole. In such an arrangement, the number ofcomplete cycles per revolution of the driving magnets will be equal tothe number of pairs of alternating North and South poles in the drivingmagnetic system. With the driver design as shown in Fig. 1 there are twocomplete cycles per revolution of the driving magnets. The transmitterwill generate two successive (positive) pulses per revolution of shaftill clockwise, and two opposite (negative) pulses per revolutioncounterclockwise. The number of cycles per revolution may be increasedby increasing the pairs of poles in the driving system; the onlylimitation on that being that the angle between adjacent North and Southpoles in the driver should be greater than the angle through which thedriven magnet is oscillated. If the number of pairs of driven poles iseven (as in Fig. 1) the driver will have like poles in diametricopposition; and consequently the driven magnet can be double as shown,with two like poles diametrically opposed. If the number of pole pairsin the driver is odd it will have unlike poles in dlametrlc opposition;and the double driven magnet will then have unlike poles in diametricopposition. Although the system will operate with a driven magnet havingonly one pole, it is desirable that it as well as the driving magnet bemultiple poled. Such an arrangement conduces to static and dynamicbalance and also increases the number of cycles and the number of highamplitude pulses which are generated for each revolution of' shaft i andthe driving magnet. In the arrangement illustratively shown, there willbe two such pulses per revolution.

From what'has been said it will readily be gathered that the operationof the ratchet mechanism involves the relative approach and passagesuccessively of a pair of unlike poles, one in the driver and the otherin the driven system, and

then of a pair of like poles. Any polar distribution in the driver anddriven system which will accomplish that alternating succession of polarpassage will operate in the manner that I intend. As an illustration, inFig. 1 the driven magnet 9 could be the driving magnet, and the drivingmagnets ll could be the driven. That can be readily seen by consideringthat the ratcheting operation depends solely on the relative movementsof the two magnet systems and that the reactions between any twoapproaching and passing poles are necessarily equal and opposite.

On the basis of the functional descriptions which have been given, Imake certain further generalizations which will now be readilyunderstood. It is of course not necessary that the several coils beequipped with cores, their presence merely increasing the efficiency ofpulse generation. But, without cores, the oscillations of generatingmagnet 8 between such relative positions as have been indicated willgenerate pulses as described.

As previously indicated, it is not necessary that element 8 bemagnetized; it can be of any magnetic material and magnetic fluxhnay bepro.

8%. vided at any place in the magnetic circuit through the cores. Forinstance the cores themselves may be magnetized; or base plate 8 may besuitably magnetized to provide the magnetic flux whether cores 2 areused or not.

If generating element 8 is a magnet (as it is preferably) then it is notnecessary that magnet l3 and the driven magnets 9 of the ratchetmechanism be separate magnets. As will be readily seen, the particularangular relationship between magnet 9 and d as shown in Fig. l. is nonecessary part of the system. Magnet 9 could just as well be parallel tomagnet t and, insofar as its flux changing functions are concerned,magnet 8 could just as well have like poles at its terminal ends. Andin'that case magnet 8, parallel to magnet '3 could be placed close to oragainst it, so that the two would not only virtually but in fact be buta single magnet. The operation of the system with such changes wouldstill be exactly as hereinbefore described.

It is not necessary that the driven magnet 9 and the driving magnet llbe co-axial, except in such a multiple arm arrangement as shown. Forinstance, if driven magnet 9 has only one arm and pole, the axis ofdriving magnet ll can be located in any position where its poles movethrough an are which is in approximate parallelism with the limitedarcuate movement of the pole of driven magnet 9.

The velocity of the snap action and the amplitude of the generated pulseis substantially independent of the speed at which the driving mag: netii is rotated, as long as that speed is relatively low as hereinbeforestated. This is a distinct advantage in systems where the initial drivermay operate at various speeds-a pressure gauge for instance. Regardlessof the rapidity of movement of the pressure gauge, each generated pulseis strong and distinct and capable of positively and reliably actuatingthe receiver of the system.

The number of impulses generated by the transmitter for each revolutionor other unit of movement of the primary driver-that is. the angularspacing of the generated impulses with relation to the angular rotationof the primary driver-will depend not only on the number of poles in thetwo ratchet magnetic systems 9 and il, but also on the ratio of gearingwhich may be inserted between the primary driver and the driving magnetsystem H. And in any situation in which gearing is thus interposed, thegearing may either have a constant ratio or a variable ratio. Thus,again to take the illustrative case of a pressure gauge, it may bedesirable to have a more accurate indication of pressures throughoutsome limited portion of the pressure gauge range. For that purpose gearsof variable ratio,

such as elliptical gearing, may be used, and arranged so that thedriving magnet l I rotates relatively faster through the critical range,and the transmitter consequently delivers a larger number of generatedpulses'per unit of movement of the primary driving pressure. gauge. In,any such arrangement the final indicator at the receiver will becorrespondingly calibrated. Figs. 2 and 2a show, by way of example, apair of intermeshing elliptic gears Illa and lob, between the shaft 10and the shaft lllc of the primary driver II.

The receiver, as here shown in illustrative and preferred form,comprises a polarized magnetic system "in combination with a physicalratchet, which acts to move an indicator (or other device or mechanism)step by step selectively in either direction depending upon the sign ofthe pulse or pulses received. One preferred form of the receivermechanism is shown in Figs. 3 to 5. In Fig. 5 the receiver as a whole isshown as being mounted in a suitable casing (dotted lines) arranged forpanel mounting. The mechanism has a coil l5 on a soft iron U-shaped corel6, and an X-shaped armature magnet ll rigidly mounted on a shaft l8 foroscillatory rotation in the gap between the free ends of the U-shapedcore It. To determine the direction of rotation of shaft l8 inaccordance with the direction of current flow through coil [5, the fourarms Ho, Ho, Ho, lid of magnet ii are magnetized alternately North andSouth, as indicated. .The armature magnet I! is biased by light springs30 and 3| to normally take the neutral position shown in Figs. 3, 5 and6 when coil I5 is de-energized. For descriptive purposes it will beassumed that coll i5 is connected in the circuit of Fig. 6 in suchmanner that upon a generation of a positive pulse in the transmitter,the end of core [6 which is adjacent arms Na and I'll) will bemagnetized to North polarity, and the other end of the core to Southpolarity. Upon such energization, the

X-shaped armature magnet will rotate in a clockwise direction until armsllb and E10 are lined up with the free ends of core l6 (see Fig. 4). Onthe other hand if the received impulse is negative, it will be assumedthat the armature magnet will be rotated in a counter-clockwisedirection to line up its poles Ila and lid with the core I6.

To prevent the armature from materially over-- travelling andoscillating about its final position a small damping eflect may beapplied to it ii desired. Under ordinary conditions the friction of thevarious parts which move with the armature will provide sufiicientdamping. The velocity at which the armature goes through its magnetvically induced movements depends mainly upon the magnetic constantsinvolved in the design and upon the inertia of the moving parts.Generally speaking, it is desirable to design those controlling factorsin such manner as to cause the movement to be fast; and restoringsprings 30 and 3| may also be proportioned to restore the armaturequickly to neutral positionywhich they do after the cessation of eachsuccessively received impulse.

Without detailed description, it will be understood that theelectro-magnet and polarized armature need not be double poled. For.instance, the same functions will be performed, although lessefficiently, if the armature has only the poles Ila and ill) and thecore IE only one pole. The double symmetric arrangement has theadvantage also of being balanced.

Upon receipt of each impulse from the transmitter the receiver armatureis oscillated through a predetermined angle to one side or the other ofits neutral position depending upon the sign of the impulse received.The general function of the physical ratchet mechanism is to advancefacing pawls and 2| which, in their neutral positions (Fig. 3) just bearon two pins 22 and 23 which may conveniently be mounted on a plate 24(see Fig. 5) which is a part of the instrument case. Pawls 20 and 2| actrespectively on ratchets 25 and 26 which have oppositely facing teeth25a and 26a. Each pawl, cooperating with its pin, acts on its ratchetlike an overriding pawl; when drawn back from its neutral position it islifted by its pin but engages and drives its ratchet v on forwardmovement from-the neutral position.

Thus, on movement of the armature clockwise to the position of Fig. 4,pawl 20 drives its ratchet 25 clockwise and pawl 2| lifts off itsratchet. On counter-clockwise movement of the armature pawl 20 rises andpawl 2! drives its ratchet 26 counter-clockwise.

The two ratchets are rigidly mounted on shaft 29 concentric with butfree from armature shaft l8. Shaft 29, which may be convenientlyjournalled in the plate 26, carries the pointer 28 which moves overcalibrated dial 2?.

The direction of the stepped movement of the finally driven member,shaft 29, is fixed with relation to the direction of movement ofarmature ll which is determined by the sign of the pulse or pulsesreceived. The sign of the pulse or pulses is determined by the directionof movement of the initial driver, whatever that may be; and the numberof pulses generated is determined by the extent of that movement.Consequently, step by step, the finally driven member is'moved inconsonance with the movements of the initial driver in each of twoopposite directions.

I consider my invention to reside not only in the telemetric system as awhole, but also in the improved transmitter and the magnetic ratchetmechanism, and in the improved receiver. While I have disclosed what atpresent I consider the preferred embodiments of the several aspects ofthe invention, it will be understood that various modifications may bemade therein which are within the true spirit and scope of the inventionas defined by the following claims.

I claim:

1. In an impulse generator, a coil, a permanent magnet member movablebetween limits in either of two opposite directions to increase themagnetic fiux through the coil on movement in one direction and todecrease the flux on opposite movement, a continuously movable drivingmemone of said limits, and then to move one of its poles toward and thenpast a like pole of the driven magnet to move said permanent magnetmember in the opposite direction to the other of said limits.

2. In an impulse generator, two coils arranged in angularly spacedrelation about an axis, a permanent magnet member pivotally mounted tolimitedly oscillate about said axis between positions near therespective coils so that on movement in either direction the magneticflux in one coil is increased and in the other is reduced, acontinuously and reversibly rotatable driving member, and a magneticratchet mechanism comprising an oscillatable driven magnet havingradially extending permanently magnetized arms and connected to thepermanent magnet member to oscillate therewith through a limited angle,said driven magnet presenting a magnetized pole at the outer swingingend of each of said arms,

and a driving magnet having radially extending it permanently magnetizedarms and connected with the driving member to rotate therewith in aplane close to the plane-of oscillation of the driven magnet, the armsof said driving magnet presenting magnetized poles of alternatingpolarity which successively approach and move past the magnetized poleof the driven magnet during the rotation of the driving magnet tocontrol the oscillation oi the permanent magnet member in onedirectionat one speed and in the opposite direction at a diflerent speedwhereby low amplitude impulses 01 one polarity and high amplitudeimpulses of an opposite polarity are generated in said coils.

3. In an impulse generator, a permanent magnet having iike poles atopposite ends thereof, a plurality of pairs of core members, a coilwinding surrounding each of said core members, a pivotally mountedgenerating magnet adapted to be oscillated etween opposite pairs of saidcore members, and a drive magnet presenting a circumferentially spacedseries 01' poles of altemating polarities and supported for rotarymovenient, the continuous rotation oi. said drive magnet in onedirection controlling said permanent magnet so as to continuouslyoscillate said gencratingmagnet with a rapid snap-like motion away fromone pair of said core members into engagement with the opposite pair ofsaid core members and with a comparatively slow motion away from saidopposite pair or core members into engagement with said one pair of coremembers, whereby a positive current impulse is induced in each of saidcoil windings during the rapid snap-like motion of said generatingmagnet and a negative current impulse is induced in each of said coilwindings during the slow motion of said generating magnet.

4. In an impulse generator, a drive magnet presenting aclrcumierentially spaced series of poles of alternating polarities andsupported for rotary movement, a driven magnet having like magneticpoles at opposite ends thereof and supported adjacent said drive magnetfor oscillatory movement in a limited arc, the continuous rotation ofsaid drive magnet in one direction driving said driven magnet to one end01' said limited.

are at the speed of rotation of said drive magnet each time a relativelyunlike pole of said driving driving said driven magnet to the oppositeend of said limited arc with a rapid snap-like movement each time a.relatively like pole of said drive magnet passes beyond a pole of saiddriven magnet, a pair of coil windings, and means controlled byoscillatory movement of said driven magnet for alternately generating acurrent flow of one polarity of relatively high, amplitude and a currentflow of an opposite polarity of relatively low am plitude in said coilwindings.

5. In an impulse generator, 9. structure includinga plurality of pairsof core members, a magnetic member mounted for movement between twopositions to form in each position a closed magnetic circuit whichincludes said magnetic member and a pair of said core members, a coilwinding inductively coupled to each of said core members, said magneticmember being so arranged with respect to said core members that currentpulses of alternate polarity are generated in said coil windings whensaid magnetic memher is continuously moved from one to the other ofitstwo positions, a drive shaft, and means including said drive shaft forimparting a snap action to said magnetic member from one to the other ofsaid positions and for slowly returning said magnetic member to said oneposition responsive to continuous rotation of said shaft in onedirection, whereby the amplitude of the pulses of one polarity arerelatively high and the amplitude of the pulses of the opposite polarityare relatively low.

GABRIEL M. GIANNINI.

REFERENCES arm!) The following references are of record in the file ofthis patent:

' UNITED STATES PATENTS Number Name Date 795,739 Stellar July 25, 19051,865,389 Reddy June 28, 1932 2,348,525 Cravath May 9, 1944 2,371,511Faus Mar. 13, 1945 2,414,688 Chambers Jan. 21, 1947 2,424,130 WakleyJuly 15, 1947 FOREIGN PATENTS Number Country Date 515,212 Great BritainNOV. 29, 1939

